Abstract : The Self-Repair Theory Investigation is a study to develop a theory of self repair in digital nets via fault diagnosis and automatic circuit replacement. The technique used is that of the Sequential Prime Implicant Form. This report shows how the factoring of the SPIF of the sequential net into sets of covering projections, each projection being a partial description of the net behavior, can be interpreted to include knowledge of impossible failure modes, knowledge of impossible state combinations, and can be used to simplify state transition. (Author)